Application of nutrient fertilizers to soil in which commercial crops, such as, for example, fruits, vegetables, grains, grasses, for example turf grasses, and other horticultural and agricultural products, are planted is one approach for increasing production and growth of such crops or grasses.
Soil nutrients, such as, nitrogen, phosphorus, potassium, and sulfur, as well as trace elements such as iron, zinc, copper, and magnesium, are useful for achieving thriving agriculture and growth of the plants. However, upon repeated planting cycles, the quantity of these nutrients in the soil may be depleted as plants utilize the nutrients. Depletion of nutrient levels in the soil may result in inhibited plant growth and decreased production per acre. To counter this effect, fertilizers have been developed to help replace the depleted vital nutrients in soil so that optimal plant growth and high yields may be obtained.
Fertilizers may be classified as either organic fertilizers or inorganic fertilizers. As used herein, the term “organic” includes having a molecular skeleton comprising a carbon backbone, such as in compositions derived from living matter. Organic fertilizers are made from materials derived from living things. Animal manures, compost, bonemeal, feather meal, and blood meal are examples of common organic fertilizers. Inorganic fertilizers, on the other hand, are manufactured from non-living materials and include, for example, ammonium nitrate, ammonium sulfate, urea, potassium chloride, potash, ammonium phosphate, anhydrous ammonia, and other phosphate salts.
Inorganic fertilizers are readily commercially available and contain nutrients in soluble form that are immediately available to the plant. Inorganic fertilizers are generally inexpensive, having a low unit cost for the desired element. In addition, the exact amount of a given element may be calculated and administered to the plant or soil. However, inorganic fertilizers suffer from disadvantages. First, inorganic fertilizers, especially nitrogen fertilizers, are subject to leaching to levels below the root of the plant. This leaching may occur as a result of rain or irrigation and may result in contamination of ground water, community drinking water, and/or wells by fertilizer components. Such leaching may render the nutrients unavailable to the plant's roots and result in wasted money being spent on the leached fertilizers. Second, excess application of the inorganic fertilizer may result in phytotoxicity, such as, burning of the plant tissue (foliar burn) and roots, particularly with young plants. Finally, inorganic fertilizers may lead to build up of toxic concentrations of salts in the soil due to heavy or non-systematic application of the fertilizer. Alternatively, chemical imbalances may develop if soil nutrient content is not closely monitored.
Organic fertilizers, on the other hand, are typically not immediately available to plants and require soil microorganisms to break the fertilizer components down into simpler structures prior to use by the plants. This break-down occurs over a time period and may provide for slower release of nutrients. Organic fertilizers usually have a low salt index, so larger amounts may be applied at one time without causing injury to the plant. In addition, buildup of toxicity in the soil is unlikely. However, the cost of organic fertilizers, on a unit cost of nutrients basis, is typically higher than the inorganic counterparts making the commercial application of conventional organic fertilizers cost prohibitive. Like inorganic fertilizers, excess application of organic fertilizers may result in burning of plant tissue (foliar burn) and roots.
In addition, organic fertilizers may not only elicit a plant growth response as observed with common inorganic fertilizers, but natural organic fertilizers may also stimulate soil microbial population growth and activities. Increased soil microbial population may have significant beneficial effects on the physical and chemical properties of the soil, as well as increasing disease and pest resistance.
There is, therefore, a need for fertilizers that do not exhibit the disadvantages of known fertilizers, but include many or all of the advantages exhibited by these products.